What are Custom/reference Data Types in java

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• Custom data types are created by defining and calling constructors of the class.

Example - We may create employee class and define its constructor.

class Employee {    private Integer id;       /** Employee constructor*/    public Employee(Integer id) {           this.id = id;    } } /** Main class*/ public class MyClass {     public static void main(String...a) {            Employee emp; //emp is pointing to null            emp=new Employee(1); //emp is pointing to object     } }

emp is reference variable of Employee type.

> emp can refer to any subClass of Employee as well

emp=new SubEmployee();

  Where SubEmployee is subClass of Employee

class SubEmployee extends Employee{    SubEmployee(){           super(1);    } }

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